Gob selectors with closed loop servo system

ABSTRACT

For positioning the scoops of a gob selector machine, for example, of the type shown in U.S. Pat. No. 3,597,187, in place of the conventional direct coupled mechanical rotary or oscillatory systems, a hydraulic power boosting system using a programmed pilot stage is used. A contoured cam drives the booster stage through a sensing servo-valve in order to remove heavy mechanical forces from the cam, greatly increase the useful life of the drive system and permit higher speed operation.

United States Patent Martin Mar. 18, 1975 GOB SELECTORS WITH CLOSED LOOPSERVO SYSTEM Primary Emminer-S. Leon Bashore Assistant Examiner-Frank W.Mi a [75] Inventor: gz Mamn Monterrey Attorney, Agent, 0r,Fi'rm-Kemon,Palmer &

exlco Estabrook [73] Assignee: Fabricacion de Maquinas, Monterrey, N.L.,Mexico [57] ABSTRACT Filedl 1973 For positioning the scoops of a gobselector machine.

[2]] App} 415,294 for example, of the type shown in US Pat. No.3,597,187, in place of the conventional direct coupled mechanical rotaryor oscillatory systems, a hydraulic U-S- Cl. power boosting ystem usinga programmed tage Int- - is used A contoured cam drives the booster tage[58] Field of Search 65/304; 91/392, 358 through a Sensing Serv0 va|vein Order to remove heavy mechanical forces from the cam, greatly inl lReferences Cited crease the useful life of the drive system and permitUNITED STATES PATENTS higher speed operation. l,823,062 9/l93l PleukharpCI 21] X 3 Claims, i g Figures 3,597,187 8/197] Trudeau 65/304pmgmgnmlems I 3,871,858

sum 1 or 3 r HQZ PATENTEU 3,871 .858

Suzi-12053 GOB SELECTORS WITH CLOSED LOOP SERVO SYSTEM BACKGROUND OF THEINVENTION AND CROSS REFERENCE TO RELATED ART to one of a plurality ofpairs of chutes extending downwardly to pairs of mold cavities arrangedin a straight line. The firing order" for example, for eight pairs ofcavities might be I, 5, 4, 8, 3, 7, 2, 6, etc. The means directing themolten glass gobs to the desired chutes is a pair of rotatably mountedscoops the upper ends of which remain coaxially aligned with theorifices of the gob former and are oscillated on axes co-axial with theorifices to feed the chutes in the desired firing order. The means foroscillating the scoops as taught in the aforementioned patent includes arotatable cam and cam follower arrangement, the cam follower beingmounted on an oscillatory member carrying a pair of ring gear segmentsin mesh with pinions carried by shafts mounting the scoops. While thisarrangement is effective, there is considerable wear on both the cam andfollower member due to loads and the ambient temperatures involved.Also, the amount of power required to drive the cam is quitelarge andconsequently a sizable primer mover is required for the purpose. All ofthese factors tend to limit the speed of operation.

An additional problem in apparatus of the prior art type occurs wheneverthere is difficulty with one or more of the molding machines. If the gobselector is permitted to continue operating it means that the mo]- tenglass dispersed to the molding machine which is malfunctioning will bewasted. If common glass is being poured there is no problem but ifleaded glass is involved it first becomes a factor of considerablefinancial magnitude because such glass cannot be collected and reheatedto produce glass of the same quality. What is required is a change ofcams to prevent dis pensing by the gob selector to the malfunctioningmachine. Unfortunately, with machines of the prior art changing the camis an operation of major proportions requiring substantially a wholeworking day.

BRIEF SUMMARY OF THE INVENTION The present invention substitutes for thecam and follower direct drive arrangement of the prior patent, aservo-hydraulic booster arrangement which reduces cam loading to aninsignificant value, greatly prolongs the life of the apparatus as awhole, and permits increased speed of operation.

In addition, by simply removing two bolts, the cam of the presentinventioncan be very quickly changed to prevent waste of expensive glassin the event of malfunction of one or more of the molding machines beingfed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of theoscillating scoops of the present invention together with some of theglass guiding chutes;

FIG. 2 is a side elevation partially in section of the apparatus shownin FIG. 1;

' FIG. 3 is a rear elevation of the apparatus shown in FIG. I; 7

FIG. 4 is a partial section on the lines 4-4 of FIG.

' FIG. 5 is a sectional view of the lines 5-5 of FIG. 2;

and

FIGS. 6, 7, and 8 are diagrammatic views useful in describing theoperation of the servo booster system.

DETAILED DESCRIPTION OF THE DRAWINGS The scoops l0 and 12 shown inperspective view in FIG. 1 are mounted on shafts l4 and 16 respectivelywhich extend through the upper wall of the housing 18 which encloses thecomponents of the hydraulic servo booster system as well asthe gearingwhich interconnects the drive system and the scoop shafts. As in theaforementioned US. patent, the firing order" is determined by the cam orother pattern control member which controls the instantaneousposition'of the shafts l4 and 16 and therefore of the scoops l0 and 12.

As shown most clearly in FIGS. 3 and 5, a pair of pinion gears 20 and 22are securedto the lower ends of shafts l4 and 16 respectively. Areciprocating piston 24 has two sets of rack teeth, 26 and 28 and theformer engage with the pinion gears 20and 22, The longitudinal positiontherefore, of the piston 24 is what determines the position of theshafts 14 and I6 and their respective scoops l0 and 12.

The drive apparatus of the present invention employs a circular cam 30continuously driven by a prime mover, not shown, through shaft 32. Anarm 34 mounted for reciprocation parallel to piston 24 carries at oneend, a roller cam follower 36 which is always in engagement withperiphery of the cam 30. Substantially at the mid-section of thereciprocating arm 34, there is a pinion gear 38 mounted for freerotation on an axis which is at right angles to the axis ofreciprocation of the arm 34. v

As shown most clearly in FIG. 2, another reciprocating arm 40 which isparallel to and spaced vertically upwardly from the arm 34 carries onits undersurface a set of rack teeth 42. The teeth 28 and 42 of thepiston 24 and arm 40 respectively, mesh with the teeth on the piniongear 38 on opposite sides thereof.

The left hand end of the arm 40 as viewed in FIG. 2 is connected todrive a spool valve, the housing for which is indicated at 44, in FIG.2. This valve is inter connected with and controls the fluid pressure inthe space at opposite ends of the piston 24 in a manner which will bedescribed with reference to the diagrammatic showing of FIGS. 6, 7 and8.

In FIGS. 6, 7 and 8 the spool valve 44 is shown as including a valve rod46 carrying a pair of valve members 48 and 50. FIG. 6 illustrates theneutral position of the servo system in which fluid flow either into orout of the chambers 52 and 54 at opposite ends of the piston 24 isblocked. This means that the piston 24 is effectively locked in theposition shown in this figure and consequently the spouts are alsolocked because they are geared to the piston 24 through the pinions 20and 22 on the lower end of shafts l4 and 16. A biasing force is appliedto the valve rod 46 from the member 40 by means of a spring 56 the exactlocation of which is shown in FIG. 2. FIG. 7 shows the parts in aposition which would not actually be achieved in practice but which willhelp to describe the operation of the system. Referring to FIG. 7, thecam 30 has rotated clockwise to a position where the radius R2which isshorter than the radius R1 is presented to the cam follower 36. Thespring 56 urges the spool valve to the left and also forces the camfollower 36 to remain in contact with the cam because the member 24remains locked in the position shown in FIG. 6.

With the valve in the position shown in FIG. 7, fluid pressure will beapplied to the right hand end of piston 24 causing it to move to theleft as shown in FIG. 8 and rotating the two pinion gears 20 and 22 in aclockwise direction. At the same time, the gear 38 is rotated in acounter clockwise direction which in turn moves the member 40 to theright which moves the spool valve back toward the neutral position ofFIG. 6.

The foregoing description is not entirely accurate, but serves toillustrate the basic relationships between the various moving parts ofthe system. In actual practice, the spool valve would never reach theextreme position illustrated in FIG. 7 because as soon as it begins tomove to the left, the ports communicating with opposite ends ofthe-pistons 24 would be cracked open and the piston24 would almostinstantaneously begin moving to the left thereby initiating movementtending to keep the spool in neutral position. As those skilled in theart will readily recognize, the above described interconnection betweenthe piston 24 and the piston 40 which always tends to return the spoolvalve to its initial position means that this is a closed loop hydraulicservo system. The only load on the cam 30 is that necessary to operatethe spool valve 44 and the actual movement of the scoops is effected byhydraulic pressure acting on opposite ends of piston 24.

While a preferred embodiment has been herein shown and described,applicant claims the benefit'of a full range of equivalents within thescope of the appended claims.

I claim:

I. Apparatus for simultaneously distributing a pair of mold chargesbeing fed from a double orifice glass feeder to the double cavity blankmolds of a plurality of glass forming machines comprising a pair ofelongated, curved deflector scoops, means supporting said scoops ingenerally side by side relationship, each scoop being formed with anopen, upwardly facing receiving end in co-axial alignment with one ofthe feeder orifices only and a lower end, a pair of rotatably mountedshafts one rigidly attached to each of said scoops repectively each ofsaid shafts having a pinion gear rigidly attached thereto;

gear means engaged with said gears and movable to rotate said shafts insynchronism;

fluid pressure means for moving said gear means in opposite directionsdepending on the direction of application of fluid pressure;

valve means for controlling the admission of fluid under pressure tosaid fluid pressure means; continuously rotatable cam means forcontrolling the position of said valve; and

means interconnecting said cam means, said fluid pressure means saidgear means and said valve in a closed loop servo system so that anymovement of said gear means in response to movement of said valve meanstends to return said valve means to its initial position.

2. Apparatus as defined by claim 1 in which said gear means comprises afirst rack mounted for reciprocating movement and terminating atopposite ends in pistons received within fluid filled cylinders, saidfluid pressure means is a source of fluid under pressure and saidinterconnecting means includes a second rack parallel to and spaced fromsaid first, a reciprocating arm parallel to said racks driven by saidcam and carrying a pinion gear meshing with both racks and a linkbetween said second rack and said valve.

3. In gob selector apparatus of the type which operates in conjunctionwith a molten glass feeder having a plurality of bottom outlet orificesfrom which separate mold charges are discharged simultaneously and whichincludes means for distributing charges for delivery by gravity toplural cavity-blank molds of a series of machines, plural mold chargedeflecting scoops equal in number to the number of said orifices, saidscoops being supported in such a position that each scoop extends frombeneath one of said orifices and is movable selectively into alignmentwith said charge distribution means, the upper end of each scoop alwaysbeing coaxially aligned with and beneath its respective orifice, meansfor oscillating said scoops in step by step fashion said meanscomprising:

a pair of rotatably mounted shafts, one rigidly connected to each ofsaid scoops and extending downwardly therefrom parallel to each other;

a pair of gears, one rigidly attached to each of said shaftsrespectively;

,a first rack member having teeth in mesh with both said gears andmounted for reciprocating movement to effect rotation of said shafts andconsequent positioning of said scoops, said rack having pistons at eachend received within fluid filled cylinders;

a second rack mounted for reciprocating movement parallel to and spacedvertically from said first rack;

an arm mounted for reciprocation between and parallel to said racks andhaving a gear rotatably mounted thereon and meshing with the teeth ofboth racks;

a rotatably driven cam for continuously changing the position of saidarm with respect to said racks; and

a spool valve connected to be reciprocated by said second rack andhaving a first pair of ports, one connected to each of said cylindersrespectively, said spool being such as to simultaneously close and opensaid ports, said valve also having an inlet port between said first pairof ports affording connection to a source of fluid under pressure and apair of interconnected outlet ports spaced outwardly of said first pairof ports.

1. Apparatus for simultaneously distributing a pair of mold chargesbeing fed from a double orifice glass feeder to the double cavity blankmolds of a plurality of glass forming machines comprising a pair ofelongated, curved deflector scoops, means supporting said scoops ingenerally side by side relationship, each scoop being formed with anopen, upwardly facing receiving end in co-axial alignment with one ofthe feeder orifices only and a lower end, a pair of rotatably mountedshafts one rigidly attached to each of said scoops repectively each ofsaid shafts having a pinion gear rigidly attached thereto; gear meansengaged with said gears and movable to rotate said shafts insynchronism; fluid pressure means for moving said gear means in oppositedirections depending on the direction of application of fluid pressure;valve means for controlling the admission of fluid under pressure tosaid fluid pressure means; continuously rotatable cam means forcontrolling the position of said valve; and means interconnecting saidcam means, said fluid pressure means said gear means and said valve in aclosed loop servo system so that any movement of said gear means inresponse to movement of said valve means tends to return said valvemeans to its initial position.
 2. Apparatus as defined by claim 1 inwhich said gear means comprises a first rack mounted for reciprocatingmovement and terminating at opposite ends in pistons received withinfluid filled cylinders, said fluid pressure means is a source of fluidunder pressure and said interconnecting means includes a second rackparallel to and spaced from said first, a reciprocating arm parallel tosaid racks driven by said cam and carrying a pinion gear meshing withboth racks and a link between said second rack and said valve.
 3. In gobselector apparatus of the type which operates in conjunction with amolten glass feeder having a plurality of bottom outlet orifices fromwhich separate mold charges are discharged simultaneously and whichincludes means for distributing charges for delivery by gravity toplural cavity-blank molds of a series of machines, plural mold chargedeflecting scoops equal in number to the number of said orifices, saidscoops being supported in such a position that each scoop extends frombeneath one of said orifices and is movable selectively into alignmentwith said charge distribution means, the upper end of each scoop alwaysbeing co-axially aligned with and beneath its respective orifice, meansfor oscillating said scoops in step by step fashion said meanscomprising: a pair of rotatably mounted shafts, one rigidly connected toeach of said scoops and extending downwardly therefrom parallel to eachother; a pair of gears, one rigidly atTached to each of said shaftsrespectively; a first rack member having teeth in mesh with both saidgears and mounted for reciprocating movement to effect rotation of saidshafts and consequent positioning of said scoops, said rack havingpistons at each end received within fluid filled cylinders; a secondrack mounted for reciprocating movement parallel to and spacedvertically from said first rack; an arm mounted for reciprocationbetween and parallel to said racks and having a gear rotatably mountedthereon and meshing with the teeth of both racks; a rotatably driven camfor continuously changing the position of said arm with respect to saidracks; and a spool valve connected to be reciprocated by said secondrack and having a first pair of ports, one connected to each of saidcylinders respectively, said spool being such as to simultaneously closeand open said ports, said valve also having an inlet port between saidfirst pair of ports affording connection to a source of fluid underpressure and a pair of interconnected outlet ports spaced outwardly ofsaid first pair of ports.